Vehicles sometimes remain running even though the vehicle is not presently moving anywhere. For example, a vehicle such as a bus carries passengers along a predefined route. At times, the bus stops at various locations along the route for an extended period of time to adhere to a posted schedule. In order to maintain the comfort of the passengers and the driver, the engine remains operable (e.g., continues to run) while the bus is stopped to keep the heating, ventilation and air conditioning (HVAC) system working. As another example, in the event of inclement weather, such as snow, or emergency situations, a vehicle may be delayed or stranded for a variable period of time. Again, the engine remains operable in these situations to keep the HVAC system working. Accordingly, a need exists for determining the duration of a stop to minimize the use of vehicle components for powering the HVAC system.